1. Field of the Invention
The present invention relates to a light-sensitive composition, a light-sensitive transfer material, a light shielding layer for a display device prepared by using the light-sensitive composition or the light-sensitive transfer material, a color filter provided with the light shielding layer for a display device, a liquid crystal display element, a substrate having the light shielding layer for a display device, and a producing method for the substrate having the light shielding layer for a display device.
2. Description of the Related Art
A color filter to be used in a color liquid crystal display and the like has a color pixel layer (R, G, B) formed on a transparent substrate, and a light shielding layer for a display device formed in gaps between the color pixels of R, G, B (red, green, blue) for improvement of display contrast, etc. In particular, a liquid crystal display element of an active matrix driving system that uses a thin film transistor (TFT) requires high light shielding properties in the light shielding layer for a display device in order also to prevent a deterioration in image quality due to current leakage in the thin film transistors caused by light.
There has been known a method of forming a light shielding layer for a display device in which, for example, a metal film such as chromium is used as a light shielding layer, producing a metallic thin film by an evaporation method or a sputtering method, coating a photoresist on the metallic thin film, subjecting the photoresist layer to exposure and development by means of a photomask having a pattern for a light shielding layer for a display device, etching the exposed metallic thin film, and subsequently releasing the photoresist layer on the metallic thin film (e.g., see “Karah TFT Ekisho Display (Color TFT Liquid Crystal Displays)” published by Kyoritsu Shuppan Co., Ltd., pp. 218-220 (Jul. 20, 1996)).
In this method, although the resulting light shielding layer for the display device can provide high light shielding effect even with small film thickness due to use of a metallic thin film, the method requires a vacuum film forming step and an etching step of using a liquid represented by the evaporation method and the sputtering method during production. This leads to higher cost, and problems such as environmental impact cannot be neglected. Also, since the light shielding layer is a metal film, reflectance is high, which causes a problem of the display contrast being low under strong external light. While there is a means of using a low reflectance, chromium film (two layers comprising metal chromium and chromium oxide, and the like), this inevitably leads to further increased costs.
Another known method of forming a light shielding layer for a display device employs a light-sensitive resin composition containing a light shielding pigment, including carbon black. More specifically, a method of forming a light shielding layer for a display device of the self alignment mode is also known, which involves, for example, forming R, G and B pixels on a transparent substrate, coating on the pixels a light-sensitive resin composition containing carbon black and subsequently exposing light to the entire surface from the surface side on which the R, G and B pixels of the transparent substrate are not formed (refer to Japanese Patent Application Laid-Open (JP-A) No. 62-9301).
Although this method allows the production cost to be lower than that of the method that etches the above-mentioned metal film, the former causes a problem in that the wall becomes too thick in an attempt to obtain sufficient light shielding properties. As a result, overlaps (bumps) occur between the light shielding layer for a display device and R, G and B pixels, whereby the evenness of the color filter deteriorates to generate cell gap irregularity of the liquid crystal display element, leading to concern about display failure such as color irregularity.